Device for determining wind velocity



May 3, 1966 K. H. RAMSAYER DEVICE FOR DETERMINING WIND VELOCITY OriginalFiled April 29, 1959 INVENTOR.

W H @vv 'my United States Patent M 3 Claims. i. 73-178) This is adivision of application Serial No. 809,860, filed April 29, 1959, nowabandoned.

Advanced self-contained navigational equipments of aircraft such asDoppler navigation systems or inertial navigation systems are oftencombined with a dead reckoning computer. The purpose of this combinationis that in the case of inoperativeness of the Doppler equipment or inthe case of failure of the Doppler or inertial equipment the position ofthe aircraft may be calculated by a continuous integration of the groundspeed vector as computed from the true airspeed vector and from the windspeed vector. For this dead reckoning computer it is especiallyimportant to know the true wind the moment when the Doppler or inertialequipment gets inoperative. Therefore, automatic wind computers weredeveloped which compute the wind speed and wind direction of thequantity and the direction of the true airspeed, the drift angle and theground speed. The object of the present invention comprises a new devicefor automatic wind finding by comparing the measured ground speed vectorwith the measured airspeed vector. It is so designed that there is nodifficulty in replacing this device with a device for automatic windfinding which compares the position which is derived from the measuredairspeed vector and an assumed wind vector with the true position whichis described in United States patent application 809,860, now apandonedbut of which this application is a continuation, or with the positionderived from VORTAC or TACAN according to US. Patent 3,082,420. It isalso easily possible to combine two or all three methods for automaticwind finding. The invention is therefore especially suitable as a partof an integrated navigation system which combines different navigationalaids to get an optimal use of them. This is an essential advantage whichin the available wind computers is not existing. A further advantage isthat the invention is simpler than the known solutions.

The principle of the invention is the following: The dead reckoningcomputer calculates from true airspeed, heading and two rectangularcomponents of the Wind speed vector, two rectangular components ofground speed which are parallel to the coordinate system for thenavigation. These calculated ground speed components are compared withthe components of ground speed derived from a Dopple or inertialnavigational system. If there are any differences between thecorresponding ground speed components the corresponding components ofwind speed are changed automatically in such a way, that the calculatedground speed components are equat to the measured ground speedcomponents.

The drawing, in a schematical representation, shows an embodiment of theinvention a chiefly mechanically operated dead reckoning computer.

In this dead reckoning computer the true airspeed is set as a vector inaccordance with the amount v and in accordance with the direction ot inthe vector mechanism 12. The true airspeed is set by a synchro remotetransmission system consisting of the synchro transmitter 13 which isbuilt into the true airspeed transmitter, of the synchro controltransformer 14, of the servomotor 15 and of the amplifier 16, wherebythe screw nut 18 arranged on the spindle 17 is readjusted by theservomotor 3,248,940 Patented May 3, 1966 15 relatively to the centrepoint M; of the vector mechanism in accordance with V The grid headingat, is likewise set by a synchro remote transmission system. This systemconsists of the synchro transmitter 19 which is operated by a compasssystem, of the synchro control transformer 20, of the amplifier 21 andof the servomotor 22. The servomotor 22 is adapted to turn the vectormechanism 12 via a worm gear until it is aligned in accordance with atWith the aid of the setting knobs 23 and 24 the wind can be set inaccordance with its components v and v by hand in parallel with the xandy-axis respectively, of the coordinate grid used as the system ofreference. On account of this the pin 27, resting against the sliders 25and 26 by spring action, is displaced in relation to the centre point Mof the wind-setting device according to v and v Both the true airspeedvector and the wind vector are vectorially added by the shears 28, theends of which are hingedly connected with the screw nut 18 (point of thevector v as well as with the pin 27 (point of the wind vector). Thevector sum corresponding to the ground speed v is represented by thedistance MS, wherein S corresponds to the centre point of the shears andM to the centre between M and M The ground speed vector MS=v is resolvedvia the rod 29 and the two sliders 30 and 31 rectangularly crossing eachother, into the components v and v parallel in relation to the xor yardsof the reference coordinate system respectively. For reasons ofsimplicity and for enabling a better understanding both the sliders 30and 31, as well as the shears 28 are shownin a staggered representation.In reality both the sliders and the shears are lying in parallelhorizontal planes, and the rod 29 is positioned vertically in relationto the plane of the shears and the sliders. By the slider 30 the ballcage 32 of the ball and disc integrator 32, 33, 34, as well as thelinear potentiometer 35 are readjusted in accordance with v By theslider 31 the ball cage 36 of the ball and disc integrator 36, 37, 38,as well as the linear potentiometer 39 are readjusted in accordance withv When the discs 33 and 37 are driven by the motor 40 with a con stantspeed, then the friction roller 34 will rotate an amount proportional tothe flight path in the x-direction, and the friction roller 38 willrotate an amount proportional to the flight path in the y-direction. Tothe friction rollers 34 and 38 there are connected the counters 41 and42 which, after having previously been set to the coordinates of thestarting point of flight, continuously indicate the map grid coordinatesx and relating to the aircraft position.

The Doppler navigation system can be caused to act upon the deadreckoning computer in the following way: The differential synchro 43 isconnected with the synchro transmitter 44 which is set by the compasssystem according to on The shaft of this differential synchro 43 isturned by the Doppler aerial unit in accordance with the drift angle a.On account of this the follow-up system connected to the output of 43and consisting of the synchro control transformer 45, of the amplifier46 and of the servomotor 47, will rotate the shaft of the resolver 48 inaccordance with the track a =ot +l1 Furthermore, the resolver 48 isconnected via the buffer amplifier 49 to the potentiometer 50, which isreadjusted by the Doppler radar system in accordance with the groundspeed v Consequently, the output voltages of the resolver 48 areproportional to v =v -cos or and v =v -sin a Via the amplifiers 51 and52 these output voltages are continuously compared with the voltages astapped from the linear potentiometers 35 and 39. The supply voltages ofthe potentiometers 35, 39 and 50* must be chosen thus that the samespeed components correspond to same output voltages. In case of anyprobable differences the Potentiometers 35 and 39 are adjusted to theoutput voltages of the resolver with the aid of the servomotors 53 and54 by correcting the wind components v and v Instead of a Doppler radarsystem there may also be used an inertial navigation system in which theground speed is calculated by measuring and integrating the horizontalaccelerations.

This methods of combining the dead reckoning computer with the groundspeed transmitter by means of the wind-correcting device designed inaccordance with the invention bears the advantage over the soleemployment of the directly measured ground speed that in the event of afailure of the ground speed transmitter the indication of the deadreckoning computer is continued on account of the exact calculated lastwind data.

The invention may also be used for the dead reckoning navigation ofmarine vessels. In this case we have to measure the speed of the vesselrelative to the water instead of the airspeed. We get then the velocityof the flow of the water instead of the wind. To meet both possibilitiesin the following claims we say vehicle for aircraft or vessel and mediumfor air or water and velocity of the medium for wind or velocity of theflow of the water.

While the principles of the invention have been described above inconnection with a specific embodiment, and particular modificationsthereof, it is to be clearly understood that this description is madeonly by way of example and not as a limitation on the scope of theinvention as set forth in the objects thereof and in the accompanyingclaims.

What is claimed is:

1. A device for determining the velocity of the medium for the automaticnavigation of vehicles moving in said medium by way of dead reckoningcomprising an automatic dead reckoning computer which calculates theposition of the vehicle from the measured quantity and direction of thevehicles speed relative to the medium and from the velocity of themedium as set in accordance with two rectangular components, elementsfor the setting of said rectangular components of the velocity of themedium, means for analogue computing two rectangular components of theground speed of the vehicle from said speed relative to the medium andsaid velocity of the medium, a Doppler navigation system measuring theground speed and the drift of the vehicle, means to resolve the groundspeed measured by said Doppler navigation system in two rectangularcomponents parallel to said ground speed components of the deadreckoning computer, means to compare said ground speed componentsdetermined by the dead reckoning computer and said ground speedcomponents determined by the Doppler navigation system and means for theautomatical setting of said elements for setting the components of thevelocity of the mediumin the dead reckoning computer in such a way thatthe ground speed components of the dead reckoning computer are equal tothe ground speed components of the Doppler navigation system.

2. A device for determining the velocity of the medium for the automaticnavigation of vehicles moving in said medium by way of dead reckoningcomprising an automatic dead reckoning computer which calculates theposition of the vehicle from the measured quantity and direction of thevehicles speed relative to the medium and from the velocity of themedium as set in accordance with two rectangular components, elementsfor the setting of said rectangular components of the velocity of themedium, means for analogue computing two rectangular components of theground speed of the vehicle from said speed relative to the medium andsaid velocity of the medium, a Doppler navigation system measuring twocomponents of the ground speed of the vehicle, means to transform theground speed components measured by said Doppler navigation system intwo rectangular components parallel to said ground speed components ofthe dead reckoning computer, means to compare said ground speedcomponents determined by the dead reckoning computer and saidtransformed ground speed components determined by the Doppler navigationsystem and means for the automatical setting of said elements forsetting the components of the velocity of the medium in the deadreckoning computer in such a way that the ground speed components of thedead reckoning computer are equal to the transformed ground speedcomponents of the Doppler navigation system.

3. A device for determining the velocityof the medium for the automaticnavigation of vehicles moving in said medium by way of dead reckoningcomprising an automatic dead reckoning computer which calculates theposition of the vehicle from the measured quantity and direction of thevehicles speed relative to the medium and from the velocity of themedium as set in accordance with two rectangular components, elementsfor the setting of said rectangular components of the velocity of themedium, means for analogue computing two rectangular components of theground speed of the vehicle from said speed relative to the medium andsaid velocity of the medium, an inertial navigation system with means todetermine two rectangular components of the ground speed of the vehicleparallel to said ground speed components of the dead reckoning computer,means to compare said ground speed components determined by the deadreckoning computer and said ground speed components determined ;by theinertial navigation system and means for the automatical setting of saidelements for setting the components of the velocity of the medium in thedead reckoning computer in such a way that the ground speed componentsof the dead reckoning computer are equal to the ground speed componentsdetermined by the inertial navigation system.

References Cited by the Examiner UNITED STATES PATENTS 2,847,855 8/1958Berger 73-178 2,936,950 5/1960 Parsons 235-61 3,007,338 11/1961 Gray eta1. 73178 ISAAC LISANN, Primary Examiner.

SAMUEL S. MATTHEWS, Examiner.

1. A DEVICE FOR DETERMINING THE VELOCITY OF THE MEDIUM FOR THE AUTOMATICNAVIGATION OF VEHCILES MOVING IN SAID MEDIUM BY WAY OF DEAD RECKONINGCOMPRISING AN AUTOMATIC DEAD RECKONING COMPUTER WHICH CALCULATES THEPOSITION OF THE VEHICLE FROM THE MEASURED QUANTITY AND DIRECTION OF THEVEHICLE''S SPEED RELATIVE TO THE MEDIUM AND FROM THE VELOCITY OF THEMEDIUM AS SET IN ACCORDANCE WITH TWO RECTANGULAR COMPONENTS, ELEMENTSFOR THE SETTING OF SAID RECTANGULR COMPONENTS OF THE VELOCITY OF THEMEDIUM, MEANS FOR ANALOGUE COMPUTING TWO RECTANGULAR COMPONENTS OF THEGROUND SPEED OF THE VEHICLE FROM SAID SPEED RELATIVE TO THE MEDIUM ANDSAID VELOCITY OF THE MEDIUM, A DOPPLER NAVIGATION SYSTEM MEASURING THEGROUND SPEED AND THE DRIFT OF THE VEHICLE, MEANS TO RESOLVE THE GROUNDSPEED MEASURED BY SAID DOPPLER NAVIGATION